Habanero Plant Not Growing

I live in Texas. I purchased a habanero plant from Wal-Mart about 3 months ago. I also purchased serrano plants. After 3 months, my habanero has not grown an inch. My serrano has produced plenty. What am I doing wrong? I now have my habanero in a small pot and it has a mix of sand and top soil. I water about twice a week. The plant is not as green as when I purchased it but it is not yellow.